Generally, a need has been recognized for what may be termed “kinder gentler stereo”.
In this context, “stereo” refers to a system for putting information on a two-dimensional, essentially flat screen surface (such as front and back projection “movie” screens, CRTs, LCDs, etc.) in a way that causes the observer to see an image in depth corresponding to the depth in the original scene. The scene could be a real scene captured by an appropriate camera system, a virtual scene generated by a computer, or a hybrid of these.
The term “kinder gentler” is provided as a contrast to what has been experienced with known conventional devices. Particularly, conventional stereo displays often involve various types of physical and mental discomfort, to varying degrees. One commonly encountered example of such discomfort is “virtual reality sickness”. Technical inconveniences have also been noted among known devices, such as specialized types of eyewear that must be worn and “viewing zones” that are often perceived to be bothersome.
At a basic level of the musculature of the human visual system, there is a well-known conflict, known as convergence-accommodation (sometimes termed “vergence-accommodation”, among other things) that makes it difficult to achieve the desired consistency among stimuli (or cues). That is, because the information is presented on a 2D “flat” screen surface, the eyes focus (i.e., accommodate) on that surface. However, the directions-of-gaze of the eyes have been found to converge not on the screen but onto a center-of-interest which generally exists someplace in front of or behind the screen at a distance corresponding to the virtual location of the point or region at the momentary center-of-interest.
The conflict between what the convergence muscles and the focusing muscles are each communicating to the brain about the scene's depth is thus a major disturbing conflict. A need has thus been recognized to overcome this and other conflicts of less severe nature.